1. Field of the Invention!
This invention relates to a slider of a slide fastener having an automatic locking mechanism realized by arranging a leaf spring fitted to the slider body and having a locking pawl and a U-shaped resilient portion disposed respectively at the opposite ends thereof such that the slider slidingly moves as the pull tab is manually operated and automatically stops once the pull tab is released.
2. Prior Art!
FIG. 7 of the accompanying drawings schematically illustrates a known slider of a slide fastener having an automatic locking mechanism of the type under consideration and disclosed by Japanese Patent Application Laid-Open No. 8-32261. It comprises a cover 3' having a pair of inner projections 35', 35' arranged longitudinally at the center of the inner surface thereof, a leaf spring 2' having a locking pawl 27' located at an end thereof, a pair of laterally extending protuberances 29', 29' and a resilient portion 28' extending between the locking pawl 27' and the protuberances 29', 29', a slider body 1' having a front attachment lug 10' located near the front opening of the slider body 1' and standing from a front area of the upper surface of the upper wing 5' of the slider body 1', said front attachment lug 10' having a central groove 12' and side recesses 55 arranged at the top of the front attachment lug 10' for receiving said protuberances 29', 29' respectively, a rear attachment lug 11' located near the rear opening of the slider body 1' and standing from a rear area of the upper surface of the upper wing 5' of the slider body 1', said rear attachment lug 11' having a vertical groove 21', a locking-pawl-insertion hole 24' for allowing the locking pawl 27' of the leaf spring 2' to pass therethrough and project into a guide channel, and a pull tab 4' having an axle 37' at an end thereof. The automatic locking mechanism of the slide fastener is constituted by said projections, 35', 35' of the cover 3', the leaf spring 2' and the front and rear attachment lugs 10', 11' and the locking-pawl-insertion hole 24' of the slider body 1' such that the protuberances 29', 29' of the leaf spring 2' are received in and preliminarily secured by the respective transversal recesses of the front and rear attachment lugs 10', 11' and the U-shaped resilient portion 28' of the leaf spring 2' is received in the central groove 12' of the front attachment lug 10' with the axle 37' of the pull tab 4' held between the leaf spring 2' and said slider body 1' while the locking pawl 27' of the leaf spring 2' is made to constantly project through the locking-pawl-insertion hole 24' of the slider body 1' into the guide channel 9' of the slider body 1' with the front end of the resilient portion 28' of the leaf spring 2' held in abutment with the projections 35', 35' on the inner surface of the cover 3' as the projections 35', 35' are received in the central groove 12' of the front attachment lug 10'.
The known slider of a slide fastener with an automatic locking mechanism as described above by referring to FIG. 7 is accompanied by a problem that it is practically impossible to make the slider including the cover show a low or thin profile due to the construction of the slider. Particularly, the U-shaped resilient portion 28' of the S-shaped leaf spring 2' is dimensionally restricted because it has to be accommodated in the narrow space defined by the attachment lugs 10', 11', so that a strong and highly resilient material cannot be used for it. Hence, such an automatic locking mechanism does not allow easy operation nor provide an reliable automatic locking effect. Additionally, the mechanism is rather complicated and involves a difficult assembling operation because the resilient portion 28' has to be securely held in position by the projection 35' of the cover 3' projecting into the groove 12' of the front attachment lug 10' with its protuberances 29', 29' received in the recesses 55 of the front attachment lug 10'.